You know how you're not dead? Specifically, I mean you know how you haven't been killed by a huge truck barreling down the highway and crushing you to custard?

For that I suggest we all take a moment and thank June McCarroll, the woman who first had the incredibly brilliant idea to paint a line down the middle of a road.

Painting a line down the middle of a road in order to define and delineate separate lanes is such a simple idea it's hard to even picture a time we didn't do it. It's so ingrained in our fundamental idea of roads, it's almost hard to imagine a road's lines as a separate concept. But, there absolutely was a time when roads didn't have any markings, and once vehicles not dragged along by slow-ass horses came onto the scene, the idea of sticking to your lane became a hell of a lot more than just polite.

As McCarroll herself recalled,

My Model T Ford and I found ourselves face to face with a truck on the paved highway. It did not take me long to choose between a sandy berth to the right and a ten-ton truck to the left! Then I had my idea of a white line painted down the center of the highways of the country as a safety measure.

McCarroll, a nurse (and later physician) with the Southern Pacific Railroad, proposed her idea to the chamber of commerce and Riverside Country Board of Supervisors, who gave the idea careful and studied ignoring. It's a likely assumption that her gender may have played a role in her inability to get the officials to take her seriously.

Eventually, McCarroll, possibly saying the phrase "screw all y'all," decided to just paint a line (allegedly with cake flour) on a road her own damn self, demonstrating empirically that this is a genuinely good idea. In the process she also ended up deciding the width of a lane of traffic. As a result of this demonstration and a letter-writing campaign, painted markings on California roads became law in November 1924. The rest of the world soon followed.

There is a competing claim to the origin of the line-down-the-middle-of-the-road idea: Edward N. Hines, a member of the Wayne County road commission, claims to have come up with painted center road lines in 1911, being inspired by watching a leaky milk wagon on a street.

His claim may be true, but I'm backing McCarroll, since A. Who transports milk in wagons? B. I live in Southern California and am feeling like I want this idea to be from here. Because.

Regardless of exactly who was first, both did come up with the idea independently, and June McCarroll certainly worked incredibly hard to get it mandatory in California, and indirectly, the rest of the world. Road markings are vastly more complex now, with yellow indicating opposite-direction traffic, broken lines, crosswalks, cat's-eyes, and much more.

But it all starts with that center line, and for that we have Dr. June McCarroll to thank.